Antimicrobial compounds and methods

ABSTRACT

Antimicrobial compounds are provided that are polymerizable. The compounds include monomers with antimicrobial properties. The compounds have cross-linking properties. The compounds may be utilized in dental and/or medical applications, including dental composites, dentures, bonding agents, sealants, resins and medical devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of co-pending application Ser. No. 14/782,936,filed Oct. 7, 2015, now U.S. Pat. No. 9,920,062; which was the UnitedStates national stage of international application PCT/US2014/033268,filed Apr. 8, 2014; which claimed benefit under 35 U.S.C. § 119(e) ofU.S. Provisional Patent Application Ser. No. 61/810,136 filed Apr. 9,2013, the entire disclosures of all of which are incorporated herein byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Development of this invention was funded by the Government under grantnumber R01DE019203 awarded by the National Institutes of Health,National Institute of Dental and Craniofacial Research. The Governmenthas certain rights in this invention.

FIELD

This invention relates generally to antimicrobial compounds, and inexemplary though non-limiting embodiments, to novel compounds thatreduce bacterial or fungal infections associated with medical and dentaldevices.

BACKGROUND

Biomaterials may be defined as any matter, surface, or construct thatinteracts with a biological system. Biomaterials are often used inmanufacturing of medical devices and dental devices, all of which tendto suffer a common problem of device-related infection. One of the mostcommon device-related infections occurs with dental devices,specifically infections associated with use of biomaterials to treatdental caries.

Dental caries, also known as tooth decay or a dental cavity, is aworldwide pandemic problem caused by a bacterial infection that may leadto progressive demineralization and/or destruction of hard tissues of atooth. Worldwide, approximately 36% of the population (approximately2.43 billion people) has dental caries in their permanent teeth. In theUnited States, dental caries is the most common chronic childhooddisease, being at least five times more common than asthma, and is aprimary pathological cause of tooth loss in children. Dental caries doesnot only affect children in the US, as upwards of 60% of adults over theage of fifty experience dental caries. If left untreated, dental cariescan lead to pain, tooth loss, and further oral infection. For largelesions, progressive decay can be treated by filing with restorativematerials, such as amalgam, composite resin, porcelain and gold.Unfortunately, these filings often have to be redone due to restorationfailure, and the site serves as a vulnerable site for further decay andinfection.

Secondary caries, also known as recurrent caries, is decay that appearsat restoration margins and is a primary cause of restoration failure.Prevention of secondary caries may be attempted through use offluoride-releasing and/or antibacterial dental materials; however,antibacterial effects of these materials, which may contain releasablereagents (e.g., chlorhexidine), have antibacterial efficacy for only ashort time (typically less than about 1 week). Also, these materialsoften suffer from poor mechanical properties due to porosity in thematerials after drug release.

Polymers with antimicrobial (mainly antibacterial and antifungal)activities, generally known as polymeric biocides or antimicrobialpolymers, have drawn interest in the fields of biomedical materials andmedical implants. See Kenawy E-R et al., The Chemistry and Applicationsof Antimicrobial Polymers: A State-of-the-Art Review, Biomacromolecules2007; 8(5):1359-1384. As polymers, the polymeric biocides are moreresistant to leaching. Common biocide moieties include quaternaryammonium, pyridinium, phosphonium, and sulfonium salts. The mechanism ofaction of quaternary compounds may be direct cationic binding to cellwall components, leading to disruption of cell wall membranes, andsubsequently leakage of cell contents and cell death. To achieve highantimicrobial efficacy, the quaternary salt typically has at least onelong-chain alkyl or substituted alkyl group, and a relatively lowtendency to form an ion-pair with a counter ion.

One of the few antibacterial monomers that have been used in dentalmaterials to date is methacryloyloxydodecyl pyrimidinium bromide (MDPB).See Imazato S. et al., Incorporation of bacterial inhibitor into resincomposite, Journal of Dental Research 1994; 73:1437-1443; Imazato S, etal., Incorporation of Antibacterial Monomer MDPB into Dentin Primer,Journal of Dental Research 1997; 76:768-772. Bactericidal activity ofthe monomer and different dental materials (primer, bonding adhesive,and composite) containing MDPB against oral Streptococci have beenstudied. See Imazato S, et al., Antibacterial Activity and BondingCharacteristics of an Adhesive Resin Containing Antibacterial MonomerMDPB, Dent. Mater. 2003; 19:313-319, and Imazato S., AntibacterialProperties of Resin Composites and Dentin Bonding Systems, Dent. Mater.2003; 19:449-457. MDPB has been reported to inhibit bacterial growth inuncured resins, in cured resins, and in bonding agents. Incorporatingantibacterial activity in a self-etching bonding agent would be ofparticular clinical importance, because self-etching bonding agentsusually have a pH higher than about 2.0, and do not effectively killacid-resistant bacteria. By contrast, a conventional phosphoric acid(37%) etching gel has pH of 0.8 and effectively kills most bacteria.

Unfortunately, most existing antimicrobial monomers contain only onepolymerizable group (usually monomethacrylate), which decreases theoverall degree of cross-linking. Since the degree of polymerizationconversion in dental composite is typically 60%-80%, an uncuredantibacterial monomer may leach out reducing antimicrobial effects andmechanical properties. Another drawback of methacrylate-based monomersand polymers is that they are susceptible to hydrolytic and enzymaticdegradation, which causes cleavage of ester bonds, and thusdeterioration of the materials.

Device-related microbial infections are not limited to dental devices;medical devices are also associated with a definitive risk.Device-related infections, such as catheter-related infections,significantly contribute to an increasing problem of nosocomial, orhospital-acquired, infections. Other medical devices that are prone todevice-related infection include prosthetic heart valves, cardiacpacemakers, total artificial hearts, joint replacements or otherorthopedic devices, as well as various shunts and catheters.Collectively, device-related infections are a wide-spread problem withlimited preventative options.

Thus, there remains an unmet need for new antimicrobial compounds havingimproved cross-linking properties and hydrolytic stability, which maylead to sustained long-term antimicrobial efficacy and protectionagainst device-related, microbial infections.

SUMMARY

In an exemplary embodiment of the present invention, a compound havingone of the following formulas:

is provided. R is a substituted or unsubstituted aliphatic or aromaticgroup having 2 to 50 carbon atoms. R′ is a substituted or unsubstitutedaliphatic or aromatic group having 2 to 50 carbon atoms, and having atleast one polymerizable group. m is a positive integer from 1 to 30. Ais one of a substituted amine, quaternary ammonium, and diammonium salt.R₁ is one of hydrogen and an unsubstituted aliphatic group containing 1to 18 carbons, benzyl, and a cyclic aliphatic or aromatic groupcontaining 5 to 18 carbons.

R and R′ may be one of R1-R6:

Y may be one of hydrogen, and an unsubstituted aliphatic groupcontaining 1 to 6 carbons. Z may be one of hydrogen, and anunsubstituted aliphatic group containing 1 to 6 carbons. n may be apositive integer from 0 to 20.

A may be one of A1-A5:

X may be one of F, Cl, Br, I, CF₃SO₃ (triflate), acetate, and gluconate.Y may be one of hydrogen, and an unsubstituted aliphatic groupcontaining 1 to 6 carbons.

At least one of R, R₁ and R′ may be acrylamide. Y may be a methyl group.Z may be one of methyl and ethyl. X may be one of Cl and Br.

L may be one of L1-L11:

Y may be a methyl group and Z may be hydrogen. Y may be hydrogen and Zmay be one of methyl and ethyl group. X may be one of Cl and Br. R₁ maybe hydrogen, and m may be one of 6, 8, 10, 11, 12, 14, 16, and 18. R₁may be one of a methyl and an ethyl group, and m may be one of 6, 8, 10,11, 12, 14 and 16. R₁ may be an unsubstituted aliphatic group containing6 carbons, and m may be one of 6, 8, 10, 11, 12, 14 and 16. R₁ may be anunsubstituted aliphatic group containing 10 carbons, and m may be one of6, 8, 10, 11, 12, 14 and 16. R₁ may be an unsubstituted aliphatic groupcontaining 12 carbons, and m may be one of 4, 6, 8, 10, 11, 12, 14 and16. R₁ unsubstituted aliphatic group containing 14 carbon, andm may beone of 2, 4, 6, 8, 10, 11, 12, 14 and 16. R₁ may be an unsubstitutedaliphatic group containing 16 carbons, and m may be one of 2, 4, 6, 8,10, 11, 12, 14 and 16. R₁ may be a benzyl group where m is one of 6, 8,10, 11, 12, 14 and 16. R and R′ may be the same.

In an exemplary embodiment of the present invention, a dental compositecontaining approximately 0.5% to approximately 10% of a compound ofclaim 1 is provided. In an exemplary embodiment of the presentinvention, a denture based material containing approximately 0.5% toapproximately 10% of a compound of claim 1 is provided. In an exemplaryembodiment of the present invention, a dental bonding agent containingapproximately 0.5% to approximately 10% of a compound of claim isprovided. In an exemplary embodiment of the present invention, a dentalsealant containing approximately 0.5% to approximately 10% of a compoundof claim 1 is provided. In an exemplary embodiment of the presentinvention, a dental resin cement containing approximately 0.5% toapproximately 10% of a compound of claim 1 is provided. In an exemplaryembodiment of the present invention, a medical device containingapproximately 0.5% to approximately 10% of a compound of claim 1 isprovided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a chart showing results of a cytotoxicity test of exemplarymonomers at various concentrations according to example embodiments ofthe present invention.

FIG. 2A is a chart showing antimicrobial activities of exemplarymonomers at various concentrations against S. mutans according toexample embodiments of the present invention.

FIG. 2B is a chart showing antimicrobial activities of exemplarymonomers at various concentrations against L. casei according to exampleembodiments of the present invention.

FIG. 2C is a chart showing antimicrobial activities of exemplarymonomers at various concentrations against P. aeruginosa according toexample embodiments of the present invention.

FIG. 2D is a chart showing antimicrobial activities of exemplarymonomers at various concentrations against S. aureus according toexample embodiments of the present invention.

DESCRIPTION

Embodiments of the present invention provide new antimicrobial monomersand polymers. Embodiments may be utilized to prevent microbialinfections, such as bacterial infections, including those associatedwith medical and/or dental devices. Embodiments of the present inventionprovide more effective monomers and improved mechanical properties ofcomposite compounds containing high antibacterial loads. Embodiments ofthe present invention include compounds containing cross-linkingantibacterial monomers. Embodiments of the present invention providemonomers having antibacterial activities as a monomer and afterpolymerization.

The invention described herein generally comprises a series ofantimicrobial compounds having the following general formulas andstructures (hereinafter, the “General Formulas”):

R and R′ may be the same or different polymerizable groups selected. Rmay be a substituted or un-substituted aliphatic or aromatic grouphaving 2 to 50 carbon atoms, and having at least one polymerizablegroup, the polymerizable group may be located in a terminal position. Amay be a substituted amine, quaternary ammonium, or diammonium salt. Lmay be a substituted or un-substituted aliphatic or aromatic linkagegroup having 1 to 100 carbon atoms and at least three bonding sites, mmay be positive integers from 1 to 30. R′ may be a substituted orun-substituted aliphatic or aromatic group having 2 to 50 carbon atoms,and having at least one polymerizable group. R and R′ may be the same ordifferent. R and/or R′ may be an acrylamide monomer. R₁ may be hydrogen,a substituted or un-substituted aliphatic or aromatic group containing 1to 30 carbons.

Embodiments of the present invention may include one or more of thefollowing options: (1) multiple polymerizable terminal groups in the R(or R′) moieties or multiple Rs each with at least one polymerizableterminal group which may form a cross-linked polymer matrix; (2)long-chain aliphatic or aromatic groups (10 or more carbon atoms) in theR and R′ moieties which may reduce hydrophilicity (water sorption)and/or increase miscibility with other dental monomers; (3) long-chainaliphatic or aromatic group (the sum of m and the number of carbon atomsin R₁ greater than 12) which may increase antimicrobial activity.

The R and R′ groups in the General Formulas may contain at least onepolymerizable moiety such as a C═C double bond, an epoxy group, anethyleneimine group, isocyanides, or thiol. R groups may include estersof acrylic or methacrylic acid, for example methyl acrylate, methylmethacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate,propyl methacrylate, isopropyl acrylate, isopropyl methacrylate,2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropylacrylate, hydroxypropyl methacrylate, tetrahydrofurfuryl acrylate,tetrahydrofurfuryl methacrylate, glycidyl acrylate, glycidylmethacrylate, glycerol mono- and di-acrylate, glycerol mono- anddi-methacrylate, ethyleneglycol diacrylate, ethyleneglycoldimethacrylate, neopentyl glycol diacrylate, neopentylglycoldimethacrylate, and trimethylolpropane triacrylate.

Other examples of R and/or R′ may include vinyl azalactone, vinylpyrrolidone, styrene, divinylbenzene, urethane acrylates ormethacrylates, epoxy acrylates or methacrylates and polyol acrylates ormethacrylates, substituted acryl amides and methacrylamides. R and/or R′may be acrylamide monomers, which may be cross-linked.

Examples of the R and R′ group may include one or more of the followingstructures R1-R6:

wherein a dotted line represents a bond between R (or R′) and L groups(or the aliphatic chain); Y may be hydrogen or an un-substitutedaliphatic group containing 1 to 6 carbons; Y may be a methyl group; Zmay be hydrogen or an un-substituted aliphatic group containing 1 to 6carbons; Z may be methyl or ethyl group; n may be an integer from 0 to20. R and/or R′ group may include structure R3, which may be anacrylamide monomer.

In the General Formula II, L may be a substituted or unsubstitutedaliphatic or aromatic linkage group having 1 to 100 carbon atoms and atleast three bonding sites. Examples of the L group may include one ormore of the following structures L1-L11 (a dotted line represents a bondbetween R and L group):

In the General Formulas, A may be a substituted quaternary ammonium ordiammonium salt. Examples of the A group may include one or more of thefollowing structures A1-A6 (the dotted bond represents a bond between Aand L groups or between A and R₁ groups):

wherein Y may be hydrogen, or an un-substituted aliphatic groupcontaining 1 to 6 carbons; Y may be methyl group; X may be F, Cl, Br, I,CF₃SO₃ (triflate), acetate, or gluconate; X may be Cl or Br.

In the General Formulas, R₁ may be hydrogen, or an unsubstitutedaliphatic group containing 1 to 18 carbons, benzyl, a cyclic aliphaticor aromatic group containing 5 to 18 carbons; R₁ may be an unsubstitutedaliphatic group containing 12 to 16 carbons or a benzyl group.

Embodiments may be copolymerized with other monomers commonly used indental materials or medical devices and/or initiators, by either heatcure, irradiation of UV or visible light (light cure), or chemicalinitiating agents (chemical cure or self-cure).

Examples formulas are given below of synthesis and characterization ofseveral precursors and embodiments of antimicrobial monomers inaccordance with this invention. All solvents were dried over 3 Åmolecular sieves and reactions were run der N₂ atmosphere. NMR spectrawere recorded at room temperature and referenced to TMS. All assignmentsare tentative. Exact masses (electrospray ionization) were obtained witha mass spectrometer. IR spectra were recorded with a FT-IR spectrometer.

Formulas 2 and 3

2-(1,3-dimethacryloyloxy)propyl 10-bromodecanoate (Formula 2)

To a 50 mL round bottom flask containing 1,3-glyceroldimethacrylate(1.9302 g, 8.4569 mmol), 10-bromodecanoic acid (0.5339 g, 2.216 mmol)and 4-dimethylaminopyridine (DMAP) (0.0250 g, 0.205 mmol) under N₂atmosphere, 5 mL dichloromethane was added followed bydicyclohexylcarbodiimide (DCC) (0.4839 g, 2.345 mmol). A whiteprecipitate forms immediately. After 3 h stirring, the slurry isfiltered over a coarse (60 M) frit and the filtrate collected. Thesolvent was then removed under reduced pressure. Purification bychromatography (2×16 cm silica), eluted with acetone/hexanes 1:19-1:9v/v, R_(f)˜0.45 (1:9), yields the product as a yellow oil (0.7490 g,1.623 mmol, 76%).

¹H-NMR (CDCl₃, δ): 6.11 (br, 2H, 2CHH′), 5.61-5.59 (m, 2H, 2CHH′),5.44-5.34 (m, 1H, (CH₂)₂CHOR), 4.44-4.22 (m, 4H, (CH₂)₂CHOR), 3.40 (t,³J_(HH)=6.8 Hz, 2H, CH₂Br), 2.32 (pseudo td, ³J_(HH)=7.5 Hz, ³J_(HH)=2.7Hz, 2H, CH₂CO₂R), 1.94 (s, 6H, 2CH₃), 1.85 (pent, ³J_(HH)=7.5 Hz, 2H,CH₂CH₂Br), 1.64-1.57 (m, 2H, CH₂CH₂CH₂Br), 1.46-1.37 (m, 2H,CH₂CH₂CH₂CH₂Br), 1.29 (br, 8H, 4CH₂); ¹³C-NMR(CDCl₃, δ): 173.4, 173.0,166.9, 166.5, 136.0, 135.91, 135.90, 126.6, 126.53, 126.51, 69.5, 69.0,62.8, 62.6, 62.2, 34.3, 34.2, 34.1, 32.9, 29.4, 29.3, 29.2, 29.1, 28.8,25.03, 24.99, 18.42, 18.40.

HRMS calcd for C₂₁H₃₂O₆BrNa⁺, 483.1353; Found, 483.1369. IR (cm⁻¹) 2928(m), 2855 (w), 1720 (s, C═O), 1638 (w, C═C), 1453 (m), 1292 (m), 1144(s), 941 (m).

2-(1,3-dimethacryloyloxy)propyl 16-bromohexadecanoate (Formula 3)

To a 50 mL round bottom flask containing 1,3-glyceroldimethacrylate(4.0808 g, 17.879 mmol), 16-bromohexadecanoic acid (3.0068 g, 8.9670mmol) and DMAP (0.0560 g, 0.458 mmol) under N₂ atmosphere, 20 mLdichloromethane was added and the solution cooled to 0° C. DCC (2.0251g, 9.8149 mmol) was added dropwise as a solution in dichloromethane (4mL) and a white precipitate formed. After 5 h stirring, the slurry isfiltered over a coarse (60 M) frit and the filtrate collected. Thesolvent was then removed under reduced pressure. Purification bychromatography (4×15 cm silica), eluted with acetone/hexanes 1:19 v/v,R_(f)˜0.5 (1:9), yields the product as an oily white solid (4.1082 g,7.5304 mmol, 84%).

¹H-NMR (CDCl₃, δ): 6.12 (br, 2H, 2CHH′), 5.61-5.59 (m, 2H, 2CHH′),5.42-5.35 (m, 1H, (CH₂)₂CHOR), 4.42-4.22 (m, 4H, (CH₂)₂CHOR), 3.41 (t,³J_(HH)=6.9 Hz, 2H, CH₂Br), 2.32 (pseudo td, ³J_(HH)=7.6 Hz, ³J_(HH)=2.8Hz, 2H, CH₂CO₂R), 1.94 (br, 6H, 2CH₃), 1.85 (pent, ³J_(HH)=7.6 Hz, 2H,CH₂CH₂Br), 1.64-1.57 (m, 2H, CH₂CH₂CH₂Br), 1.45-1.38 (m, 2H,CH₂CH₂CH₂CH₂Br), 1.33-1.23 (m, 20H, 10CH₂); ¹³C-NMR (CDCl₃, δ): 173.5,173.0, 166.9, 166.5, 136.0, 135.91, 135.89, 126.6, 126.5, 126.4, 69.6,69.0, 62.8, 62.6, 62.2, 34.4, 34.2, 34.1, 33.0, 29.79, 29.77, 29.76,29.7, 29.61, 29.60, 29.4, 29.25, 29.21, 28.9, 28.3, 25.1, 25.0, 18.40,18.38.

HRMS calcd for C₂₇H₄₅O₆Br, 567.2292; Found, 567.2291. IR (cm⁻¹) 2922(s), 2852 (m), 1722 (s, C═O), 1655 (m, C═C), 1453 (m), 1293 (m), 1148(s), 941 (m).

Formulas 4 and 5

2-(1,3-dimethacryloyloxy)propyl10-(1-(1-azonia-4-azabicylco[2.2.2]octyl))decanoate bromide (Formula 4)

To a 50 mL round bottom flask containing Formula 2 (1.2948 g, 2.8063mmol) and 1,4-diazabicyclo[2.2.2]octane (DABCO) (0.3169 g, 2.8249 mmol)under N₂ atmosphere, 3 mL dichloromethane was added and the solidsdissolved. After 18.5 h, the solvent was removed under vacuum.Purification by chromatography (2×15 cm silica), eluted withdichloromethane/methanol 1:9 v/v, R_(f)˜0.1, yields the product as aclear oil (0.5961 g, 1.039 mmol, 37%).

¹H NMR (CDCl₃, δ): 6.10 (br, 2H, 2CHH′), 5.61-5.59 (m, 2H, 2CHH′),5.39-5.32 (m, 1H, (CH₂)₂CHOR), 4.40-4.20 (m, 4H, (CH₂)₂CHOR), 3.65 (t,³J_(HH)=7.3 Hz, 6H, 3N⁺CH₂CH₂N), 3.54-3.49 (m, 2H, N⁺CH₂), 3.26 (t,³J_(HH)=7.3 Hz, 6H, 3N⁺CH₂CH₂N), 2.31 (pseudo td, ³J_(HH)=7.5 Hz,³J_(HH)=2.8 Hz, 2H, CH₂CO₂R), 1.92 (s, 6H, 2CH₃), 1.75 (br, 2H, CH₂),1.62-1.54 (m, 2H, CH₂), 1.36-1.32 (m, 4H, CH₂), 1.27 (br, 6H, 3CH₂);¹³C(CDCl₃, δ): 173.5, 173.1, 167.0, 166.6, 135.85, 135.83, 135.81,126.8, 126.7, 126.6, 69.5, 68.9, 64.8, 62.7, 62.7, 62.2, 52.7, 45.5,34.3, 34.1, 29.3, 29.2, 29.1, 29.0, 26.5, 25.0, 24.9, 22.3, 18.4, 18.42.

HRMS calcd for C₂₇H₄₅O₆N₂ ⁺, 493.3272; Found, 493.3283. IR (cm⁻¹) 3411(m, br, H₂O), 2927 (m), 2856 (w), 1719 (s, C═O), 1637 (w, C═C), 1455(m), 1293 (m), 1149 (s), 943 (m).

2-(1,3-dimethacryloyloxy)propyl16-(1-(1-azonia-4-azabicylco[2.2.2]octyl))hexadecanoate bromide (Formula5)

To a 50 mL round bottom flask containing Formula 3 (1.0061 g, 1.8442mmol) and DABCO (0.3169 g, 2.8249 mmol) under N₂ atmosphere, 3 mL ethylacetate was added and the solids dissolved. After 6 days, the solventwas removed under vacuum. Purification by chromatography (2×15 cmsilica), eluted with dichloromethane/methanol 1:9 v/v, Rf˜0.1, yieldsthe product as a clear oil (0.8000 g, 1.216 mmol, 66%).

¹H-NMR (CDCl₃, δ): 6.06 (br, 2H, 2CHH′), 5.55 (br, 2H, 2CHH′), 5.36-5.28(m, 1H, (CH₂)₂CHOR), 4.36-4.15 (m, 4H, (CH₂)₂CHOR), 3.62 (t, ³J_(HH)=7.1Hz, 6H, 3N⁺CH₂CH₂N), 3.46-3.38 (m, 2H, N⁺CH₂), 3.24 (t, ³J_(HH)=7.1 Hz,6H, 3N⁺CH₂CH₂N), 2.30-2.23 (m, 2H, CH₂CO₂R), 1.88 (s, 6H, 2CH₃), 1.71(br, 2H, CH₂), 1.59-1.50 (m, 2H, CH₂), 1.33-1.26 (m, 4H, 2CH₂), 1.19(br, 16H, 8CH₂); ¹³C(CDCl₃, δ): 173.5, 173.1, 167.0, 166.5, 135.89,135.86, 135.8, 126.7, 126.6, 126.5, 69.5, 68.9, 64.8, 62.8, 62.6, 62.2,53.7, 52.7, 45.6, 34.4, 34.2, 29.82, 29.79, 29.7, 29.6, 29.4, 29.3,29.2, 26.6, 25.1, 25.0, 22.4, 18.43, 18.42.

HRMS calcd for C₃₃H₅₇O₆N₂ ⁺, 577.4211; Found, 577.4190. IR (cm⁻¹) 3402(m, br, H₂O), 2922 (m), 2852 (m), 1721 (s, C═O), 1637 (w, C═C), 1456(w), 1293 (m), 1152 (s), 941 (m).

Formula 6

2-(1,3-dimethacryloyloxy)propyl16-N,N-dimethylbenzylammoniumhexadecanoate bromide (Formula 6)

To a 50 mL round bottom flask containing Formula 3 (1.0288 g, 1.8858mmol) and dimethylbenzylamine (0.285 mL, 0.256 g, 1.90 mmol) under N₂atmosphere, 2 mL acetonitrile was added and the mixture heated to 50° C.After 48 h, the reaction was allowed to cool to rt and the solvent wasremoved under vacuum. Purification by chromatography (2×15 cm silica),eluted with dichloromethane/methanol gradient, 3%-10% v/v, Rf˜0.5,yields the product as a clear oil (1.0920 g, 1.6041 mmol, 85%).

¹H-NMR (CDCl₃, δ): 7.64 (t, ³J_(HH)=7.9 Hz, 2H, Ph), 7.52-7.40 (m, 3H,Ph), 6.10 (br, 2H, 2CHH′), 5.59 (br, 2H, 2CHH′), 5.41-5.33 (m, 1H,(CH₂)₂CHOR), 5.03 (s, 2H, CH₂Ph), 4.41-4.20 (m, 4H, (CH₂)₂CHOR),3.54-3.49 (m, 2H, CH₂N⁺), 3.28 (s, 6H, N⁺(CH₃)₂), 2.31 (pseudo td,³J_(HH)=7.5 Hz, ³J_(HH)=2.8 Hz, 2H, CH₂CO₂R), 1.79 (br, 2H, CH₂), 1.67(s, 6H, 2CH₃), 1.63-1.54 (m, 2H, CH₂), 1.36-1.29 (m, 4H, 2CH₂), 1.23(br, 16H, 8CH₂); ¹³C-NMR (CDCl₃, δ): 173.5, 173.1, 166.9, 166.5, 135.83,135.80, 135.77, 133.4, 130.8, 129.3, 127.6, 126.7, 126.6, 126.5, 69.5,68.9, 67.5, 63.9, 62.7, 62.6, 62.1, 49.8, 34.3, 34.2, 29.72, 29.70,26.6, 29.5, 29.4, 29.3, 29.2, 29.1, 26.4, 25.0, 24.9, 23.0, 18.4, 18.3.

HRMS calcd for C₃₆H₅₈O₆N⁺, 600.4259; Found, 600.4247. IR (cm⁻¹) 3404 (w,br, H₂O), 2923 (m), 2852 (m), 1720 (s, C═O), 1637 (w, C═C), 1455 (m),1293 (m), 1151 (s), 940 (m).

Formula 7

16-bromohexadecanol (Formula 7)

A 100 mL round bottom flask equipped with magnetic stirring bar wascharged with 16-bromohexadecanoic acid (1.68 g, 5 mmol) in THF (20 mL)and BH₃/THF was added dropwise at 0° C. The reaction mixture was allowedto slowly warm to rt and was stirred overnight. 30 mL water was addedthen the product was extracted using ether (3×25 mL). The organic layerwas washed by water and brine, dried over anhydrous Na₂SO₄, filtered andthe solvent was removed under vacuum to give Formula 7 as a white solid(1.472 g, 4.6 mmol, 92%).

¹H-NMR (CDCl₃, δ): 3.62 (t, 2H, CH₂OH), 3.39 (t, 2H, CH₂Br), 1.86-1.82(m, 2H, CH₂CH₂OH), 1.55-1.41 (m, 2H, CH₂CH₂Br), 1.30-1.25 (m, 24H,12CH₂); ¹³C-NMR (CDCl₃, δ): 63.3, 34.3, 33.1, 30.1, 29.9, 29.8, 29.7,29.0, 28.4, 6.0.

Formulas 8 and 9

16-(1-(1-azonia-4-azabicylco[2.2.2]octyl))-1-hexadecanol bromide(Formula 9)

A 100 mL round bottom flask equipped with magnetic stirring bar wascharged with 1,4-diazabicyclo[2.2.2]-octane (4 mmol),16-bromohexadecanol (1.28 g, 4 mmol) and EtOAc (30 mL). The white solidprecipitated and was collected by filtration, washed with cold EtOAc anddried under vacuum to give Formula 9 as a white solid (1.32 g, 3.06mmol, 77%).

¹H-NMR (CDCl₃, δ): 3.55-3.52 (t, 2H, CH₂OH), 3.40-3.36 (t, 6H, 3CH₂N⁺),3.27-3.17 (m, 8H, 3CH₂N, CH₂N⁺), 1.72-1.48 (m, 4H, 2CH₂), 1.39-1.24 (m,24H, 12CH₂); ¹³C-NMR (CDCl₃, δ): 61.8, 52.33, 52.27, 52.2, 44.9, 32.5,29.6, 29.5, 29.44, 29.39, 29.2, 29.0, 25.8, 21.6.

HRMS calcd for C₂₂H₄₅ON₂, 353.3526; Found, 353.3562.

Formulas 10 and 11

16-(1-azonia-4-azabicylco[2.2.2]octyl)hexadecylmethacrylate bromide(Formula 11)

A 100 mL round flask equipped with magnetic stirring bar was chargedwith 1-(16-(hydroxyhexadecyl-4-azoniabicyclo[2.2.2]octane)) bromide 1.3g, 3 mmol and dichloromethane (30 mL) and was placed in an ice bath.After the reaction flask was cooled for 15 min, methacryloyl chloride(3.2 mmol) was added via syringe over 10 min. The reaction mixture wasstirred at 0° C. for 2 h and then room temperature overnight. Thereaction mixture was quenched by adding saturated aqueous K₂CO₃ (150mL). The aqueous layer was extracted with chloroform (3×30 mL). Thecombined organic extract was washed sequentially with saturated aqueousNaHCO₃ (2×20 mL) and brine (2×20 mL), dried over anhydrous MgSO₄,filtered and concentrated under reduced pressure. The crude product waspurified on silica gel column with EtOAc:MeOH (3:1) as mobile phase.After removal of the solvent under vacuum, Formula 11 was isolated as awaxy, white solid (1.14 g, 2.28 mmol, 76%).

¹H-NMR (CDCl₃, δ): 6.08 (s, 1H, C═CHH′), 4.14 (t, 2H, CH₂O), 5.60 (s,1H, C═CHH′), 3.40-3.36 (m, 6H, 3CH₂), 3.27-3.18 (m, 8H, 4CH₂), 1.93 (s,3H, CH₃), 1.71-1.64 (m, 4H, 2CH₂), 1.39-1.30 (m, 24H, 12CH₂); ¹³C-NMR(CDCl₃, δ): 167.6, 137.0, 124.8, 64.8, 62.4, 52.3, 52.22, 52.18, 29.54,29.51, 29.48, 29.46, 29.4, 29.3, 29.13, 29.09, 28.5, 25.9, 21.6, 17.2.

HRMS calcd for C₂₆H₄₉O₂N₂, 421.3789; Found, 421.3792.

Synthesized monomers (Formulas 4-6, 10, and 11) andmethacryloyloxyundecyldi-methylbenzylammonium bromide (Formula 1) weretested for biocompatibility (cytotoxicity). Human gingival fibroblastswere obtained from extracted molars from patients with healthy gingivalfollowing informed consent as prescribed in an approved IRB protocol.Gingival fibroblasts were maintained in MEM containing 10% fetal calfserum (FCS) and 200 units/mL penicillin and 200 μg/mL streptomycin.Cells were grown in 48-well plates for 24 h prior to exposure to themonomers. The growth media containing 0.1% dimethylsulfoxide (DMSO) weresupplemented with 10⁻⁴ M, 10⁻⁵ M, 10⁻⁶ M and 10⁻⁷ M concentrations offive newly synthesized exemplary monomers (Formulas 4-6, 10, and 11) andadded to the cells for 24 h. MEM served as a control for cytotoxicity.Cell survival was visualized using a fluorescent esterase substrate(Calcein-AM) and a inverted fluorescent microscope. Cell survival wasquantified using a fluorescent multi-well plate reader. As shown in FIG.1, Formulas 4, 10 and 11 show little cytotoxicity at 10⁻⁴ Mconcentration. The dimethacrylate monomers containing a hexadecyl alkylchain (Formulas 5 and 6) both show significant cell death at 10⁻⁴ M butgood biocompatibility at concentrations of 10⁻⁵ M and below.

Accordingly, embodiments of the present invention have shown goodbiocompatibility (less cytotoxic than BisGMA, a commonly used dentalmonomer). Biomaterials must be compatible with the biological system itis designed for, such as the human body. For biomaterials that will beused in the human body, issues pertaining to biocompatibility must beresolved before a product can be placed on the market and used in aclinical setting.

Evaluation of antimicrobial activities of Formula 1 and synthesizedmonomers (Formulas 4-6, 10, and 11) was also performed. Streptococcusmutans was grown in brain heart infusion (BHI, Difco Laboratories,Detroit, Mich.), Lactobacillus casei was grown in MRS medium (Difco),Staphylococcus aureus and Pseudomonas aeruginosa were grown inTrypticase Soy Broth (TSB; Difco). They all were grown under staticconditions in an 37° C. aerobic chamber with (for S. mutans only) orwithout 5% CO₂. For antimicrobial assay, these bacteria were cultivatedusing a modified semi-defined biofilm medium (BM) with glucose (18 mM)and sucrose (2 mM) (BMGS) as the supplemental carbohydrate sources.Antimicrobial efficacy was measured using an automated growth curveanalysis system. Overnight cultures were transferred to fresh medium andallowed to grow to mid-exponential phase, when they were properlydiluted in BMGS and allowed to grow in the automated growth curveanalysis system with and without inclusion of Formula 1 and synthesizedmonomers (Formulas 4-6, 10, and 11). All antimicrobial monomers weredissolved in DMSO at 10⁻² M concentration and serial dilutions were madeto achieve the desired concentrations (10⁻⁴ M-10⁻⁷ M). All experimentswere run in triplicate. The results are shown in FIG. 2. Certainmonomers showed levels of antibacterial activity comparable tochlorhexidine. Highest levels of antibacterial activity were observedfor Formulas 5 and 6.

Embodiments of the present invention include cross-linking monomers thatmay form 3-dimensional cross-linked polymer network with high mechanicalproperties and chemical stability. This characteristic is an improvementover existing antimicrobial monomers, which contain only onepolymerizable group, minimizing chances of leaching out of thebiomaterial. Embodiments may include cross-linking acrylamide monomers.

Certain embodiments of the present invention also have higher hydrolyticstability (i.e., better resistance to hydrolytic and enzymaticdegradation) than current methacrylate-based antimicrobial monomers.Accordingly, embodiments of the present invention retain theiranti-microbial properties at the site of use longer.

Embodiments of the present invention may be used in dental materials,such as composites, bonding agents, sealants, resin cements, liners,endodontic materials, and infiltration resins, and dental devices.

In still other embodiments, the present invention may be used inbiomedical materials and devices, such as catheter tubes, bone graftingmaterials, skin grafting materials, scaffolds for tissue engineering.

Other embodiments of the present invention include, but are not limitedto, compounds and/or methods for: water treatment, medical andhealthcare products, food applications, textile products, and/orresearch purposes (e.g., cell culture).

Embodiments may include a dental composite containing approximately 0.5%to approximately 10% of an antimicrobial compound according to one ofthe General Formulas. Further embodiments may include a denture basedmaterial containing approximately 0.5% to approximately 10% of anantimicrobial compound according to one of the General Formulas. Stillfurther embodiments may include a dental bonding agent containingapproximately 0.5% to approximately 5% of antimicrobial compoundaccording to one of the General Formulas. Embodiments may include adental sealant containing approximately 0.5% to approximately 10% of anantimicrobial compound according to one of the General Formulas. Furtherembodiments may include a dental resin cement containing approximately0.5% to approximately 10% of an antimicrobial compound according to oneof the General Formulas. Still further embodiments include a medicaldevice containing approximately 0.5% to approximately 10% of anantimicrobial compound according to one of the General Formulas.

While embodiments are described with reference to variousimplementations and exploitations, it will be understood that theseembodiments are illustrative and that the scope of the invention is notlimited to them. Many variations, modifications, additions, andimprovements are also possible. Support for the present invention may befound in the attached documents and figures, all of which are expresslyincorporated herein in their entirety by reference hereto.

What is claimed:
 1. A compound having the structure:

wherein R and R′ may be the same or different; and R and R′ areindependently selected from the group consisting of R1, R2, R3, R4, R5,and R6:

wherein m is an integer from 1 to 30; wherein n is an integer from 0 to20; wherein A is A1:

wherein X is selected from the group consisting of F, Cl, Br, I, CF₃SO₃(triflate), acetate, and gluconate; wherein Y is hydrogen or anunsubstituted aliphatic group containing 1 to 6 carbons, and wherein thevarious Y groups may be the same or different; wherein Z is selectedfrom the group consisting of one hydrogen atom, two hydrogen atoms, andan unsubstituted aliphatic group containing 1 to 6 carbons; wherein R₁is selected from the group consisting of hydrogen, an unsubstitutedaliphatic group containing 1 to 18 carbons, benzyl, and a cyclicaliphatic or aromatic group containing 5 to 18 carbons; wherein, forclarity, it is noted that R₁ and R1 are different; and wherein L isselected from the group consisting of L3, L4, L5, L6, L7, L8, L9, L10,and L11:


2. The compound of claim 1, wherein R is R1, R′ is R1, each Y is methyl,and L is L7; whereby said compound has the structure:


3. The compound of claim 2, wherein X is F or Br, m is 14, and R₁ isbenzyl.
 4. The compound of claim 1, where at least one of R and R′ isacrylamide.
 5. The compound of claim 1, wherein X is selected from thegroup consisting of F, Cl, Br, I, CF₃SO₃ (triflate), acetate, andgluconate.
 6. The compound of claim 1, wherein each Y is a methyl group.7. The compound of claim 1, wherein each Y is an ethyl group.
 8. Thecompound of claim 1, wherein Z is methyl or ethyl.
 9. The compound ofclaim 1, wherein each Y is a methyl group, and Z is hydrogen.
 10. Thecompound of claim 1, wherein each Y is hydrogen, and Z is a methyl orethyl group.
 11. The compound of claim 1, wherein R₁ is benzyl, andwherein m is 2, 3, 4, 6, 8, 10, 11, 12, 14, 16, or
 18. 12. The compoundof claim 1, wherein R₁ is a methyl or ethyl group, and wherein m is 6,8, 10, 11, 12, 14, 16, or
 18. 13. The compound of claim 1, wherein R₁ isan unsubstituted aliphatic group containing 3, 4, 6, 8, 10, 11, 12, 14,16, or 18 carbons; and wherein m is 2, 3, 4, 6, 8, 10, 11, 12, 14, 16,or
 18. 14. The compound of claim 1, wherein R and R′ are the same.
 15. Adental composite containing 0.5% to 10% of the compound of claim
 1. 16.A denture base material containing 0.5% to 10% of the compound ofclaim
 1. 17. A dental bonding agent containing 0.5% to 5% of thecompound of claim
 1. 18. A dental sealant containing 0.5% to 10% of thecompound of claim
 1. 19. A dental resin cement containing 0.5% to 10% ofthe compound of claim
 1. 20. A medical device containing 0.5% to 10% ofthe compound of claim 1.